[CLIENT-1495] Tentatively check if a connection is allowed to avoid launching too many goroutines

Author: khaf

CHANGELOG.md

@@ -7,6 +7,10 @@
 
     - Allows reading of boolean types from the server, supported in Aerospike server v5.6. The current client will not support writing boolean type to the server. That features will be supported in the upcoming Go client v5.
 
+  * **Fixes**
+
+    - [CLIENT-1495] Tentatively check if a connection is allowed to avoid launching too many goroutines.
+
   * **Fixes**
 
     - Implements correct and re-triable Scans for the Reflection API.

node.go

@@ -541,6 +541,33 @@ func (nd *Node) getConnection(deadline time.Time, timeout time.Duration) (conn *
 	return nd.getConnectionWithHint(deadline, timeout, 0)
 }
 
+// newConnectionAllowed will tentatively check if the client is allowed to make a new connection
+// based on the ClientPolicy passed to it.
+// This is more or less a copy of the logic in the beginning of newConnection function.
+func (nd *Node) newConnectionAllowed() error {
+	if !nd.active.Get() {
+		return types.ErrServerNotAvailable
+	}
+
+	// if connection count is limited and enough connections are already created, don't create a new one
+	cc := nd.connectionCount.IncrementAndGet()
+	defer nd.connectionCount.DecrementAndGet()
+	if nd.cluster.clientPolicy.LimitConnectionsToQueueSize && cc > nd.cluster.clientPolicy.ConnectionQueueSize {
+		return types.ErrTooManyConnectionsForNode
+	}
+
+	// Check for opening connection threshold
+	if nd.cluster.clientPolicy.OpeningConnectionThreshold > 0 {
+		ct := nd.cluster.connectionThreshold.IncrementAndGet()
+		defer nd.cluster.connectionThreshold.DecrementAndGet()
+		if ct > nd.cluster.clientPolicy.OpeningConnectionThreshold {
+			return types.ErrTooManyOpeningConnections
+		}
+	}
+
+	return nil
+}
+
 // newConnection will make a new connection for the node.
 func (nd *Node) newConnection(overrideThreshold bool) (*Connection, error) {
 	if !nd.active.Get() {
@@ -581,7 +608,7 @@ func (nd *Node) newConnection(overrideThreshold bool) (*Connection, error) {
 
 	// need to authenticate
 	if err = conn.login(&nd.cluster.clientPolicy, nd.cluster.Password(), nd.sessionToken()); err != nil {
-		// increment node errors if authenitocation hit a network error
+		// increment node errors if authentication hit a network error
 		if networkError(err) {
 			nd.incrErrorCount()
 		}
@@ -627,7 +654,10 @@ func (nd *Node) getConnectionWithHint(deadline time.Time, timeout time.Duration,
 	}
 
 	if conn == nil {
-		go nd.makeConnectionForPool(hint)
+		// tentatively check if a connection is allowed to avoid launching too many goroutines.
+		if err = nd.newConnectionAllowed(); err == nil {
+			go nd.makeConnectionForPool(hint)
+		}
 		return nil, types.ErrConnectionPoolEmpty
 	}